Method of making manifolds



Patented Dec. 25, 1945 METHOD OF MAKmd AnmoLDs Robert Long, Muskegon,

ican Porcelain Enamel Company,

Mich., lassigncr to Amer- Muskegon,

Mich, a corporation of Michigan No mavmi Application February 10, 194-2, Serial N0. 430,239

2 Claims. (01. 117-129) The present invention relates to a manifold capable of withstanding oxidation at the temperatures to which it is subjected in the operation of internal combustion engines, and has to do with the method of making such a manifold.

Prior manifolds such as are in use with airplane engines are unsatisfactory in that these manifolds -must be frequentlyreplaced because of oxidation thereof due to 'the'hot' gases passing through them- The exhaust manifolds of air cooled airplane engines operate at temperatures of the order of 1250 B. to 1500 B. which is suflicient to cause oxidation of present known manifolds. Stainless steel is the most common material in use today forthe purpose, but this material is expensive and is not capable of completely withstanding tures to which the manifold is subjected by the products of combustionof-an internal combustion engine.

It is an object of my manifold made of metal, preferably of ordinary wrought steel, having a non-metallic of vitreous coating which will not be destroyed by the hot gases encountered in the operation of internal combustion engines. v 1 7 A further object is to provide an impervious vitreous coating on a manifold which prevents the oxidizing components of gases'from attacking and oxidizing the metal of which the manifold is made. g

A further object is the provision of a method of coating a manifold to prevent oxidization thereof.

The coating of my invention is impervious to gases and is resistant to high temperatures so.

that it is not essentialthat .metal of which the manifold is made be ofgood grade or expensive character. Entirely satisfactory results may be attained by the use'of wrought steel. Further,

the coating i economical tomanufacture and may be applied to a wrought metal tube or the like with a minimum of effort and expense.

It will be understood that the coating may be employed in many other instances in which it is desired to protect a surface against the deteriorating effects of high temperatures and oxidizing components of gases and the like.

Now in order to acquaint those skilled in the art with the manner of utilizing my invention I shall describe a specific embodiment of my invention as it relates to the manufacture of a manifold.

An ordinary wrou ing' or the like suitable for use as a manifold is first pickled to remove all grease, oil, and rust and the like.

invention to provide a htsteel or other metaltub In order to remove the grease.

oxidation at the temperain. asolution of sulphuric acid of a strength of 6 to 7% and at a temperature of F. for about 15 minutes. The acid is then rinsed off and the steel tube next neutralized to remove all traces of acid. This maybe accomplished by placing the steel tube in a neutralizer solution of boraxand soda ash for about 5 minutes. The strength of this solution preferably is 0.25% sodium oxide and should be at a temperature of about -180 degrees F. Other cleaning meth-- ods or ingredients may be employed if desired.

A coating for the steel tube is made up as follows: A first frit is made in accordance with the following formula and in about the amounts of the'identified components or ingredients as folents are calcined or roasted together to render the frit insoluble in' water. calcining is well known in the art and'is also frequently referred to as fritting. broken upafter calcining sothat it may be readily handled'and weighed;

- A second frit is made in accordance with the following. formula and in about the amounts of the identified components or ingredients as follows: Rasorite lbs. Feldspar 217 /2 lbs. Quartz 140% lbs. Soda ash 52 lbs. Sodium nitrite 25 lbs. Fluorspar -4 43 /2 lbs. Zircon 33%lbs. Calcium carbonate -24 fiilbs. Manganese. dioxide 11 lbs. Nickel oxide 4 lbs. 10 oz. 3 lbs.

Cobalt oxide Preferably the frit is ground or them together with a mill addition comprising the following components or ingredients which are.

added to the nine parts of the first frit and the one part of the second frit in the following percentages of the sum of the parts of frits 1 and 2.

Per cent Clay (enameling clay) 7.0 Feldspar 10.5 Borax .75 Sodium nitrite .125 Magnesium carbonate .125 Water 50.0

The mixture is then ground in the milling apparatus until an enamel is formed of which about 6 or 7% will remain on a 200 mesh screen.

After the frits 1 and 2 and the mill addition have been ground to a fineness of the character above noted, water is added to the enamel until the amount deposited upon a test sheet is one ounce per square foot, dry. This refers to the actual weight of enamel per square foot on the tube after all the water has been deleted. After the enamel has been brought to this consistency, the steel tubes are coated preferably by dipping them in the enamel. The tubes are then preferably positioned in a. suitable dryer to remove all water from the coating. Thereafter, the steel tubes are placed in a suitable furnace and burned at a temperature of the order of 1620 degrees F. for about 8 or 9 minutes. The tubing is then ready for use as a manifold. If desired the coating may be applied by other than dipping. Pref- K erably both the inner and outer surfaces are coated but in certain instances it may be desired or only essential to coat a single surface. This may be accomplished in any suitable manner.

A chemical analysis of the coating after the burning Step above referred to is as follows:

Per cent About Silica 50.2 Alumina 6.7 Boric oxide 13.3 Sodium oxide 17.0 Potassium oxide 3.6 Calcium oxide 6.7 Manganese dioxide 1.6 Nickel oxide 0.4 Cobalt oxide 0.6 Zirconium dioxide 0.1

It is calculated that there is about a 0.3% ignition loss as a result of the burning step.

The coating thus provided is impervious to oxidizing componentsof gases and the like at temperatures of the order of 1250 F. to 1500 which is the range of temperatures to which air cooled exhaust manifolds of internal combustion en gines are heated. This temperature range of air cooled exhaust manifolds of airplane engines represents the maximum temperature range to which manifolds of internal combustion engines are heated and it will be observed therefore that my invention is suitable for other types and characters of manifolds. The finished coating is of a vitreous character and of dark blue color. The coating is hard and brilliant. I have found that the finished coating will satisfactorily withstand a temperature of the order of 1500 F. and further is not readily damaged by temperatures of the order employed in the burning step of my 1 method.

It will-appear that I have provided a manifoldwhich is capable of withstanding the temperatures to which it is heated by the hot gases of an internal combustion engine. Also the coating prevents oxidation of the manifold by I the surrounding air at the temperature to which it isheated by the hot gases or products of combustion of an internal combustion engine. It will be understood that the composition of the coating of my invention is not limited to use with a manifold, but may be readily applied to any surface which it is desired to protect 'from the oxidizing effects of gases and from deteriorating effect of high temperatures.

I claim:

1. The method of treating a metal manifold which comprises, forming a first frit of the following ingredients:

Feldspar About 185 lbs. Quartz About 209% lbs. Rasorite About 209 lbs.

' Soda ash About 43 lbs. Sodium nitrite About 34% lbs. Fluorspar About 44% lbs. Manganese dioxide About 14 lbs.

7 Cobalt oxide About 4 lbs. 13 oz.

' Nickel oxide About 3 lbs. 12 oz. forming a second frit of the followin ingredients:

Rasorite About 195% lbs. Feldspar About 217 /2 lbs. Quartz About 140 lbs. Soda ash About 52 lbs.

Soda nitrate About 25 lbs. Fluorspar About 43% lbs. Zircon About 33% lbs. Calcium carbonate About 24%; lbs. Manganes dioxide About 11 lbs. Nickel oxide About 4 lbs. 10 oz. Cobalt oxide v About 3 lbs.

taking nine parts by weight of the first frit with one part by weight of the second frit and milling said parts with a mill addition comprising the following component in the following percentages of the sum of said parts:

Per cent Clay About 7 Feldspar About 10.5 Borax About .75 Sodium nitrite About .125 Magnesium carbonate About .125 Water About 50 to form an enamel, coating at least one surface of said manifold with said enamel, drying said coating, and burning said coating.

2. The method of treating a wrought steel manifold which comprises, forming a first frit of the following ingredients:

Feldspar About lbs. Quartz About 209 lbs. Rasorite About 209 lbs.

Soda ash About 43 /2 lbs. Sodium nitrite About 34% lbs. Fluorspar; About 44% lbs. Manganese dioxide About 14 lbs. Cobalt oxide About 4 lbs. 13 oz. Nickel oxide About 3 lbs. 12 oz.

forming a second frit of the following ingredients;

taking nine parts by weight of the first frit with one part by weight oi the second frit and milling said parts with a mill addition comprising the following components in the following percentages of the sum of said parts:

Per cent Clay About '7 Feldspar About 10.5 Borax About .75 Sodium nitrite About .125 Magnesium carbonate About .125 Water About 50 to form an enamel of a fineness so that the major portion thereof is passable through a 2'00 mesh screen, adding water to said enamel until the amount deposited on a test sheet is one ounce per square foot, dry, depositing a coating of said enamel on at least one surface of said manifold, drying said coating and burning said coating at a temperature of about 1620 F, for about nine minutes.

ROBERT LONG. 

